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Triple Gas Electron Multipliers (GEM) for slow and fast neutrons were employed at the n_TOF facility at CERN as online beam imaging monitors and for energy spectra measurements via the time-of-flight technique. The detectors were exposed to the neutron spectrum ranging from thermal to 1 GeV, produced by spallation of 20 GeV/c protons in a lead target with a maximum intensity of 7·10 12 protons per pulse. The spectrum and the 2D count distribution of the neutron beam were measured and compared at two distances from the target, 185 m and 200 m. The detectors showed radiation hardness, linear response and the ability to monitor the beam profile online with high spatial resolution. [ABSTRACT FROM AUTHOR]

A reliable and highly scalable Internet of Things (IoT) end-to-end data infrastructure has been developed for environmental radiation monitoring at the European Organization for Nuclear Research (CERN) based on a low-power wide-area network (LPWAN). The proposed system, called Waste radiation MONitoring (W-MON), consists of an interconnected network of thousands of highly sensitive and ultralow-power gamma radiation sensors acting as long range (LoRa) transceivers. The aim of the system is to improve and automatize the radiological controls of conventional waste containers. The end devices measure the radiation levels in the waste containers on a continuous basis and send the data periodically to the LoRaWAN network server. The network has been deployed in an outdoor environment covering hundreds of hectares. A set of web-based user applications for real-time monitoring, data visualization, and status control of the devices have been designed based on open-source tools. The data pipeline infrastructure has been designed to allow an easy integration into the overall CERN Radiation and Environment Monitoring Unified Supervision service (REMUS). [ABSTRACT FROM AUTHOR]

Purpose: Commercially available systems for ion beam reference dosimetry in water are mainly based on ionization chambers. In those systems, a large number of small detectors are typically arranged in a two‐dimensional (2D) array or matrix to achieve high spatial resolution (order of several millimeters) and large field coverage at the same time. The goal of this work was to investigate the reliability of a detector of superior spatial resolution to perform three‐dimensional (3D) ionization measurements in carbon ion pencil beams. Methods: The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region (with 2.8 cm3 × 2.8 cm3 × 0.3 cm3 volume), three gas electron multipliers (GEMs) for signal amplification and four Timepix ASICs with 55 µm pixel pitch and a total of 262,144 pixels. An integrated system was designed and built, which consists of a commercial water phantom with a three‐axis motorized arm, a reference large‐area ionization chamber for signal normalization to the beam output and the GEMPix itself. Measurements at different depths in water have been performed at the Italian National Centre for Oncological Hadrontherapy (CNAO) with three carbon ion beam energies. Lateral beam profiles measured with the GEMPix at the shallowest depth were compared to those measured with radiochromic EBT3 films in air in the position of the reference ionization chamber. The Timepix readout was calibrated in energy by using one independent depth scan with carbon ions of 150 mm range. Bragg peak curves were also simulated using the Monte Carlo FLUKA code as a reference. Results: Beam profiles measured with the GEMPix were smooth and showed similar shape and full width at half maximum when compared to those measured with radiochromic EBT3 films. Smooth, reproducible Bragg curves were obtained with statistical uncertainties of about 2%, matching FLUKA simulations of the Bragg curves within 15% for most data points. This difference is partially explained for the measurement with carbon ions of 150 mm range by a saturation effect in the GEMs. The high granularity of the readout allowed to produce 2D images of the deposited dose at different depths, as well as 3D data distributions. Conclusions: This paper demonstrates the capability of the GEMPix detector to measure the 3D dose distribution of carbon ions in water for a clinical pencil beam reliably. In the future, the detector area will be increased to cover fields of scanned beams. Measurements at higher beam intensities and with protons are planned. [ABSTRACT FROM AUTHOR]

The study of Soft X-ray emission can be a source of fundamental information, particularly for what concerns tokamaks and plasma diagnostics, but also in general in the fields of high energy and nuclear physics. Detection systems based on Gas Electron Multipliers (GEM) technology can be of particular use in the context of X-ray analyses, being relatively low cost while maintaining good spatial and temporal resolution and capability to sustain high counting rates (up to MHz/mm2). The development of these new and improved detectors is thus of interest, especially in the research about diagnostic and control of machines for fusion energy. In this work, the performance of a new triple-GEM detector, characterized by an aluminum metallic coating on both layers of the GEM foils, is presented and a comparison is made with the more conventional design employing copper coating. The performances of an aluminum-coated GEM (Al-GEM) detector and of a standard copper-coated GEM (Cu-GEM) detector in revealing quasi-monochromatic X-ray beams coming from different fluorescence materials are compared. The Al-GEM detector is shown to less suffer the issue of unwanted background on the signal caused by the presence of copper inside the detector itself. The suppression of this noise source encourages the use of Al-GEM detectors to perform spectroscopy in harsh environments, such as tokamak machines, where soft X-rays are useful probes to control different plasma properties and parameters. [ABSTRACT FROM AUTHOR]

The GEMTEQ is a gaseous detector with Gas Electron Multipliers for signal amplification and Timepix ASICS as highly pixelated readout. It is based on the GEMPix detector and designed for microdosimetry. This paper describes the vacuum chamber developed to house the three versions of the GEMTEQ and to operate the detector in sealed-mode and at low pressure. A sealed version avoiding the need of a gas system offers clear advantages for its transport and use, e.g., for measurements at a clinical particle therapy centre. Operating the detector at a pressure lower than atmospheric increases the spatial resolution, one of the key parameters in microdosimetry. A gas-tight detector housing, a pumping system, and a pressure and temperature monitoring system were developed and tested in operational conditions. These extensive tests have proven the vacuum chamber to be gas tight and well suited for the foreseen microdosimetric measurements: the GEMTEQ can be operated for several weeks at 1000 mbar without noticeable degradation of the detector signal. First measurements have been carried out successfully at pressure values as low as 200 mbar. Further tests are planned to reach the design goal of 10 mbar. Overall, the vacuum chamber fulfils the requirements for a sealed-mode and low-pressure operation of the GEMTEQ. Measurement campaigns using this setup for example for LET measurements in hadron beams have already been carried out and will be discussed in forthcoming papers. [ABSTRACT FROM AUTHOR]

Abstract: This paper is focused on the soft X-ray tomography system set-up at Tore Supra (DTOMOX) and the recent developments made to get precise information about plasma features from a raw or inverted data. The ultimate aim is not only to use this information in real time for visualisation but also for potential feedback, with a particular emphasis on the optimisation of the reconstruction technique and on simple analysis tools developed for an automatic treatment of these inverted data. Recent progress made on the optimisation of free parameters used for the tomographic inversion will be explained. Finally, future techniques using advanced imaging detector will be presented. In particular, preliminary investigation on the use on Tore Supra of Gas Electron Multiplier (GEM) detector for imaging purposes will be described also including some first observations in situ. [Copyright &y& Elsevier]

A triple gas electron multiplier (GEM) detector has been built and characterized in a collaboration between ENEA, INFN and CEA to develop a soft X-ray imaging diagnostic for magnetic fusion plasmas. It has an active area of 5×5cm2, 128pixels and electronics in counting mode. Since burning plasma experiments will have a very large background of radiation, this prototype has been tested with contemporary X-ray, neutron and gamma irradiation, to study the detection efficiencies, and the discrimination capabilities. The detector has been preliminarily characterized under DD neutron irradiation (2.45MeV) up to 2.2×106 n/s on the detector active area, showing a detection efficiency of about 10−4, while the detection efficiency of X-rays is more than three orders of magnitude higher. The detector has been also tested under DT neutron flux (14MeV) up to 2.8×108 n/s on the whole detector, with a detection efficiency of about 10−5. The calibration of the γ-rays detection has been done by means of a source of 60Co (gamma rays of energy 1.17MeV and 1.33MeV) and the detection efficiency was found of the order of 10−4. Thanks to the adjustable gain of the detector and the discrimination threshold of the electronics, it is possible to minimize the sensitivity to neutrons and gamma, and discriminate the X-ray signals even with very high radiative background. [ABSTRACT FROM AUTHOR]

Thermal neutron detection technologies alternative to 3He, featuring a rate capability matching the high flux expected at the European Spallation Source (ESS), are one of the main present challenges of neutron science. A new thermal neutron detection technology was recently developed named the BAND-GEM, a Gas Electron Multiplier (GEM)-based detector provided with a borated 3D converter to reach high efficiency. In this paper the results of a count rate test performed on the BAND-GEM at the ORPHEE reactor are presented. The results show that the detector can easily reach a neutron count rate of 2 MHz/cm2 while maintaining a good linearity and it is able to reach 8 MHz/cm2 with a measurable loss of linearity η and with no sign of instability. [ABSTRACT FROM AUTHOR]